*2.4.2* Phytoseius plumifer *performance feeding on corn pollen*

Although phytoseiid mites have been mainly described as predators of mites and small insects, several species can feed and reproduce on pollen as well. The potential of phytoseiids to regulate phytophagous mites at low equilibrium densities has been more attended recently and studies have examined some of the characteristics that contribute to the survival of populations at low prey densities, such as feeding on pollens [31]. Pollen is utilized as an easy food source for phytoseiid mites rearing and also has been recognized as an important factor in the successful biological control of spider mites [32].

McMurtry and Croft [31] categorized the life style of phytoseiids based on feeding habitats and related biological and morphological traits. The life styles are: Type I, specialized predators of *Tetranychus urticae*; Type II, selective predators of tetranychids; Type III, generalist predators that may feed on pollen but perform better on prey; Type IV, specialized pollen feeders-generalist predators. *Phytoseius* species are categorized as Type III predators. Knowledge of the nutritional value of different plant pollens for *P. plumifer* could be important not only for mass rearing of the mite, but also for a better understanding of its population dynamics in the field.

In our previous work we described the effect of corn pollen on the life table parameters of *P. plumifer* at laboratory conditions according to Carey [33] method. We showed that *P. plumifer* can develop and reproduce on corn pollen under laboratory conditions, so the predator can persist in the field when its main prey is scarce or absent. Survival rate was 97% at immature stages and adult females appeared in 10th day and started laying eggs. On day 16 a sharp decline observed in survival curve and all of individuals died until 20th day (**Figure 2**). By comparing with Hamedi et al. [34] results we can conclude that corn pollen as lonely food source increases longevity of immature stages and decreases longevity and fecundity of adults of the predator considerably, although the predator can develop and reproduce successfully.
